Changes in antioxidant defense system in gills of Capoeta umbla caught from Uzuncayir Dam Lake, Turkey

• Results obtained from this research can be use as a guide for biomonitoring to assess toxicity level in aquatic environment.
• Measurement of SOD, CAT, GSH-PX, GSH and MDA may be promising indicators of an oxidant impact on aquatic organisms.
• This new approach has an potential for usage in routine monitoring or assesments researches of all aquatic environments.
• This study confirmed use of biomarkers in assessment of potential biological effects of organic pollution in Capoeta umbla.

The aim of this work was to determine the seasonal changes in the activities of selected biomarkers in Capoeta umbla (Heckel, 1843) caught from Uzuncayir Dam Lake (Tunceli, Turkey) and to evaluate the effects of environmental factors on these activities. Fish were sampled on seasonal basis, and superoxide dismutase, catalase, glutathione peroxidase activities and levels of glutathione and malondialdehyde in gills were determined. Significant variations of oxidative stress biomarkers were observed between seasons and sites. The results of this study show that seasonal variations of oxidative stress responses and lipid peroxidation in gills of C. umbla are sensitive to the contaminants present in water of Uzuncayir Dam Lake and selected parameters are in valuable biomarkers for monitoring of water systems, since they give an early warning signal of effects of xenobiotics on aquatic organisms at molecular levels which help to prevent their effects at organismal level.